title: Operating room ventilation with laminar airflow shows no protective effect on the surgical site infection rate in orthopedic and abdominal surgery.
abstract: OBJECTIVE
  To evaluate whether operating room (OR) ventilation with (vertical) laminar airflow impacts on surgical site infection (SSI) rates.
  
  
  METHODS
  Retrospective cohort-study based on routine surveillance data.
  
  
  METHODS
  Sixty-three surgical departments participating voluntarily in the German national nosocomial infections surveillance system "KISS" were included (a total of 99,230 operations). Active SSI surveillance was performed according to the methods and definitions given by the US National Nosocomial Infection Surveillance system. Surgical departments were stratified according to type of OR ventilation used: (1) turbulent ventilation with high-efficiency particulate air-filtered air, and (2) HEPA-filtered (vertical) laminar airflow ventilation. Multivariate analyses were performed by the generalized estimating equations method to control for the following variables as possible confounders: (a) Patient-based: wound contamination class, ASA score, operation duration, patients' age and gender, endoscopic operation; (b) Hospital-based: the number of beds in the hospital, its academic status, operation frequency, and long-term participation in KISS.
  
  
  RESULTS
  The risk for severe SSI after hip prosthesis implantation was significantly higher using laminar airflow OR ventilation (1.63 < 1.06; 2.52>), as compared with turbulent ventilation. The adjusted odds ratios for the other operative procedures analyzed were: knee prosthesis 1.76 < 0.80, 3.85>; appendectomy 1.52 < 0.91, 2.53>; cholecystectomy 1.37 < 0.63, 2.97>; colon surgery 0.85 < 0.49, 1.49>; and herniorrhaphy 1.48 < 0.67; 3.25>.
  
  
  CONCLUSIONS
  Unexpectedly, in this analysis, which controlled for many patient and hospital-based confounders, OR ventilation with laminar airflow showed no benefit and was even associated with a significantly higher risk for severe SSI after hip prosthesis.
authors.affiliation: Charité-Universtitätsmedizin Berlin, Berlin, Germany. christian.brandt@kgu.de
authors.forename: Christian
authors.initials: C
authors.lastname: Brandt
authors.forename: Uwe
authors.initials: U
authors.lastname: Hott
authors.forename: Dorit
authors.initials: D
authors.lastname: Sohr
authors.forename: Franz
authors.initials: F
authors.lastname: Daschner
authors.forename: Petra
authors.initials: P
authors.lastname: Gastmeier
authors.forename: Henning
authors.initials: H
authors.lastname: Rüden
mesh_terms: D000005:Abdomen / Q000601:surgery; D000389:Air Conditioning; D000391:Air Microbiology; D001062:Appendectomy; D019644:Arthroplasty, Replacement, Hip; D019645:Arthroplasty, Replacement, Knee; D002763:Cholecystectomy; D015331:Cohort Studies; D013505:Digestive System Surgical Procedures; D005374:Filtration / Q000295:instrumentation; D005858:Germany; D006801:Humans; D016017:Odds Ratio; D009873:Operating Rooms / Q000592:standards; D019637:Orthopedic Procedures; D011159:Population Surveillance; D012189:Retrospective Studies; D013530:Surgical Wound Infection / Q000517:prevention & control*; D014691:Ventilation / Q000379:methods*